1. Field of the Invention
The present invention relates to a seat slide position detection device for a vehicle.
2. Description of the Related Art
In an automobile, the driver's seat, the front passenger seat, or the like is equipped with an air bag device to protect the occupant of the seat in the event of a collision of the vehicle. The air bag device is normally stored in the steering wheel or the instrument panel. Upon detection of an impact generated in the collision of the vehicle, an explosion takes place in an inflator and inflates the air bag into a balloon shape. Thereby, the occupant is prevented from striking against the steering wheel or the instrument panel in the collision of the vehicle.
Meanwhile, if the air bag is fully deployed with constant operating force, preferred effects of the air bag may not be obtained, depending on the physical size of the occupant. In view of this, an air bag device has been developed in recent years, which uses the seat position in a vehicle as a guide in estimating the physical size of the occupant and deploys the air bag in a stepwise manner in accordance with the seat position in the vehicle, to thereby obtain the effects of the air bag. Further, to detect the seat position required for the air bag device, a variety of seat slide position detection devices for a vehicle have been developed which use a magnetic sensor.
For example, according to Japanese Unexamined Patent Application Publication No. 2006-281813, an upper rail fixed to a seat is slidably assembled to a lower rail fixed to the floor of a vehicle. The lower rail is bent and formed into a substantially U-shape having an open upper portion. Meanwhile, the upper rail is bent and formed into a substantially U-shape having an open lower portion. A proximity sensor (corresponding to the position sensor of the present application) is provided inside the upper rail as a position detection device. Further, the proximity sensor has a detection surface facing a side surface of a locking plate provided inside the lower rail. The proximity sensor detects the side surface of the locking plate to thereby detect the seat position.
Herein, in the case of an electric sliding seat device, a motor, a ball screw mechanism, and so forth for sliding a seat may be provided inside the upper rail and the lower rail. Therefore, if the electric sliding seat device has a proximity sensor disposed inside the upper rail, as in the above patent application publication, the proximity sensor may interfere with the motor, the ball screw mechanism, and so forth provided inside the upper rail. Therefore, the seat slide position detection device for a vehicle according to the above patent application publication may not be applicable to the electric sliding seat device.
In view of the above, according to Japanese Unexamined Patent Application Publication No. 2005-41245, a seat slide sensor (corresponding to the position sensor of the present application) for detecting the seat position in the anteroposterior direction of a vehicle is provided outside the upper rail. The seat slide sensor is mounted on the upper rail such that the lower surface of the seat slide sensor (corresponding to the sensor detection surface of the present application) is disposed above and separated from the lower rail (corresponding to the detection target portion of the present application) by a predetermined distance. Further, the seat slide sensor is attached with a protection cover surrounding the sensor. The protection cover includes a first wall portion and a second wall portion. The first wall portion is positioned above and separated from the seat slide sensor by a first predetermined distance. The second wall portion is positioned lateral to and separated from the seat slide sensor by a second predetermined distance, and extends lower than the seat slide sensor. Further, the seat slide sensor has a detection surface facing the upper surface of the lower rail, and detects the presence or absence of the lower rail, to thereby detect the seat position.
A seat slide position detection device for a vehicle having a seat slide sensor disposed outside the upper rail and the lower rail, as in the second patent application publication, is expected to be applicable to the electric sliding seat device.